Kromer, 48, was taken into custody by deputies in Walton County, Fla., just before 2 a.m. and was released on bond about an hour later, authorities said.
In a news release posted on Facebook, the Walton County Sheriff's Office claimed Kromer got into an confrontation with three boys regarding the use of beach chairs near an access point for Inlet Beach. The alleged victims told deputies Kromer grabbed their fishing pole and threw it into the water and pushed one of the boys to the ground before punching him in the face.
The boy who was punched said Kromer threatened to kill his family if he reported him to authorities, the report stated.
Walton County Sheriff Michael A. Adkinson Jr. said the case remains under investigation.
The Bills released a statement regarding Kromer's arrest: “We are aware of the report and in the process of gathering the facts.”
Kromer joined the Bills in January under new head coach Rex Ryan after being fired as the Chicago Bears' offensive coordinator. He served briefly as the New Orleans Saints interim coach in 2012 after head coach Sean Payton was suspended by the NFL for his alleged role in the Saints' bounty scandal.
The Associated Press contributed to this report.